i am replacing the origonal 60amp lucas alternator on my 69 man 2+2(with air) with a new alternator with a inbuilt regulator.Would someone please advise which wires i use to connect to the new unit .From the blog i believe i no longer need the 3AW or the regulator(both nice and new)The wiring harness is also new.Thanks in anticipation JOHN
At the 3AW, take the WL wire and connect it to the AL wire. You can use a short jumper, or just change one of the connectors. At the alternator side, connect the AL wire to the D+ of your alternator. This may be labeled differently, depending on what alternator your choose. If it’s a Delco, for example, it will be labeled “1”. The F+ and F- can be taped off, they will not be used.
Pretty much everything else in the alternator circuit is no longer needed: the voltage regulator, relay, and 3AW.
Just a word of warning: with this type of alternator, the ignition light is actually an active part of the circuit. If the bulb blows, the alternator won’t charge. And you can’t use an LED to replace the bulb. If you are concerned about blowing the bulb, you can install a 330 ohm resistor in parallel with the bulb as a backup.
should be able to handle that ok.Im proposing to use a Lucas LXA119 65amp alternator.the mounting positions are ok and the reverse fan from the old alt can be adapted
Interesting choice. I see a bunch of these on the market, but I’m not sure if they’re copies or real Lucas parts. Some of them seem to have a W connection, which gives you more wiring options. If you send me a close up photo of the back of the alternator, I’ll try to be more specific about the wiring.
Thanks ,its being marketed over here by one of our major and reputable parts suppliers so should be ok(! ?),will send a pic when it arrives JOHN
That’s really odd. W is an AC connection, which bypasses the diodes, the equivalent of the Lucas AL connection. It can be used to drive the 3AW if you want to keep that. Just connect the AL wire to the W terminal, and the F+ wire to D+. This would mean you retain the relay and the 3AW.
But unless you can verify that the small terminal is D+, it’s not clear how it was intended to be installed. It could be a one wire alternator, with no D+ at all. Is there a Lester number somewhere on the packaging? This would be a five digit number.
With the exception of the plastic attachment on the left (which looks like a cable guide for the connection posts), this alternator appears very similar to the one that a PO installed on my 3.8 S1.
I identified it as a Lucas A127 RH, though I can’t recall how…
That one appears to have a Mercedes pinout. Two B+'s and a D+ in a socket. There’s a plastic terminal holder that clips to the socket and is held in place with a spring bail. You can get the connector tor those at a Mercedes dealer.
Here’s a new one:
alternator Terminal identification guide.pdf (203.5 KB) i came across this identification sheet which indicates the W is for power to a electronic tacho if previously used.Would the smaller unmarked terminal be for the AL and should be marked I (as in eye) or D+ as in your notes.Is there a bench test i could do to verify this
yes basically definately the same alternator
The W is an AC feed, so can be used to drive a tach (frequency changes with RPM), but it will work fine as an AL lead. The smaller terminal is likely a D+ lead, which is used to provide bootstrap current to the regulator. But that would need to be confirmed.
your spot on Got onto OEX and they confirmed the unmarked terminal is D+.Its all mounted and ready to go,just waiting on a smaller drive belt as the pulley is smaller.Not many auto shops where i live
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